1. Field of Invention
The technical scope of the invention is that of automatic identification processes using bar codes, such as, for example, the code known under the name PDF (Portable Data File) 417 symbology.
2. Description of Related Art
The PDF bar code generated a lot of interest with the increased supply of corresponding scanners. This bar code is known to provide a substantial encoding capacity, which is not the case for other known, widely distributed, bar codes. This encoding capacity is such that this bar code is no longer quantitatively different but qualitatively different from other identification tools. Its identification role does not consist in merely calling for data, but in providing data directly at a very competitive level of reliability and system possession cost with respect to that implemented in different technologies such as chip cards, PCMCIA cards, or radio labels.
However, in the gaps that bi-dimensional symbologies have created, the limit of 1,000 octets offered by the PDF 417 bar codes remains unsurpassed by other previously mentioned supports. For more details, reference may be made to the document published by Association of Identification Manufacturers in UNIFORM SYMBOLOGY SPECIFICATION PDF 417.
How to distribute and retrieve information on several PDF 417 bar codes are known. However, reading must be carried out in the exact order in which the information was encoded in order to obtain a coherent message. Moreover, when the information is of the binary type, a loss has been noted leading to a recognition by the control bar code that causes disturbances. Lastly, there is no way to control the integrity of the information.